Letting rats live a little longer by ceasing to poison and trap them proved a killer move by the Bream Head Conservation Trust.

The successful predator removal scheme involved ceasing the regular poison - not laying for a few months so rats lost their wariness about it, letting them breed up in numbers, then hitting them with a ground-laid 1080 bomb.

It was a double whammy because then stoats ate the rats that ate the poison and died too.​The result of the major operation that started in April was very satisfying, according to head ranger Adam Willetts.

"This was a planned and desired outcome from the toxin removal, that rats would be in better numbers to consume 1080 pellets from bait stations and be the delivery vector to stoats via hunting predation, and therefore transfer secondary poisoning," Mr Willetts said in the group's newsletter.

"The rat and mustelid traps were also shut down from mid-July so they too were not catching the temporarily valuable rats. (I cannot believe I just typed that - it feels so wrong)."

Mr Willetts said he was very proud of the volunteers who stepped up, "without a grizzle, often in the rain", to help with hand-delivering two rounds of pre-feed and then the 1080 toxin to 1160 bait stations all over the reserve.

Key stakeholder groups and boundary owners were notified before the delivery of the toxin and signs were erected at the key reserve entry points.

Volunteers came from Kerikeri, Russell, Whangarei and Whangarei Heads.

The operation was supported by Department of Conservation (DOC) staff and equipment.